Electric odometer drive

ABSTRACT

An electrically operated odometer system having a panel-mounted indicator unit and a remote transmission-mounted sensor unit, each characterized by compactness and smoothness of operation. Both units are related by an electrical circuit means employing a unique switching arrangement dependent in part upon the use of a wobble-type planocentric gear reduction to achieve space reduction and improve operation.

Umted States Patent [1 1 [111 3,812,332 Woodward May 21, 1974 [541 ELECTRIC ODOMETER DRIVE 3.307.782 3/1967 Henssetal .Q 25/95 R [75] Inventor: Gary Ewwdward, Ann Arbor 3.659.780 5/1972 Woodward... 235/951:

M h. 1c Primary Examiner-Stephen J. Tomsky Asslgneei q Motor p y Deafbom, Attorney, Agent, or Firm-Joseph W. Malleck; Keith MlCh. L. Zerschling [22 Filed: Dec. 5, 1972 211 App]. No.: 312,431 [571 ABSTRACT An electrically operated odometer system having a pa- 5 Cl 235/95 R, 23 5 /96, 324/167 nel-mounted indicator unit and a-remote transmission- 51 Int. Cl G0lc 22/00 mounted Sensor unit, each Characterized y p 5 Field f Search 2 5 5 R 0 5 ness and smoothness of operation. Both units are re- 324/167, 168, 7 73/490 lated by an electrical circuit means employing a unique switching arrangement dependent in' part upon 5 References Cited the use of a wobble-type planocentric gear reduction UNITED STATES PATENTS to achieve space reduction and improve operation. 3,166,245 H1965 Maschke 235/95 Ii 5 Claims, 11 Drawing Figures 2') .Zkilrzmwm fin?! 7%z 2flf //Z7m z?fi 2/? h W) e if fi/m/zr I fi M i /f 624/ fi/Z/(fl Y 4/ fli /war J/dr )ZzIW/I /v/z?2/? 7741971311! Dr/w I w lla a7,

2252' ML, yL/zWZa/a PATENTEDHAY 21 I974 SHEET 3 (IF 4 ELECTRIC onoMETER DRIVE BACKGROUND OF THE INVENTION Various means have been employed to convert a speed signal (taken from some part of the vehicle) to a pulse for actuating electrically driven odometer rolls which are of relatively small size and mass. Such means must take a continuous movement, such as that of a transmission gear, and convert to an indexing movement so as to progressively bring new and proper numerals into view within the indicator unit.

Electrically operated odometer systems are known which have indicator units consisting of a solenoid ratchet or stepper motor to drive the odometer rolls. The solenoid ratchet or stepper motor is provided with pulses of electrical energy taken from a source through switching mechanisms controlled by the rotation of a member sensitive to vehicle speed. These systems have a very low output torque and, hence, are subject to malfunction and binding of the odometer rolls due to the mechanical tolerances associated with the manufacture of rolls and other mechanisms. In addition, these systems have high noise characteristics, relatively low efficiency, and can be difficult to incorporate in modern vehicles.

To overcome the above disadvantages, other prior art approaches have included a series of worm gears which aided in reducing the noise problem, rendering high torque, out most importantly lacked compactness and ease of installation in modern vehicles.

SUMMARY OF THE INVENTION The invention herein is directed to overcoming the deficiencies of both prior art approaches. It comprises two aspects:

a. the provision of a panel mounted indicating unit for a vehicular odometer system, the unit employing wobble-type planocentric power-transmitting means thereby rendering a more compact unit. The planocentric means is effective to provide high ratio reduction in rotation while maintaining relatively high efficiency.

b. the combination of the wobble-type planocentric transmitting means in conjunction with double-acting switches having their contacts placed to altemately connect parallel paths therebetween. Thus upon actuation of a first switch (related to the remote sensing unit) in response to a predetermined distance traversed by the vehicle, the motor for the odometer indicating unit will be energized for movement causing other planocentric means to function and actuate a second switch; after a predetermined rotation of the motor, the second switch is moved to another operating position, thereby shutting off the motor, and preparing the circuit for the next change in the first switch to repeat the cycle.

BRIEF SUMMARY OF THE DRAWINGS FIG. 1 is a schematic representation of the total odometer system embodying this invention;

FIG. 2 is an exploded view, in perspective, of the indicator unit of FIG. 1;

FIG. 3 is an exploded view, in perspective, of some components of the sensor unit of FIG. 1;

FIG. 4 is an enlarged elevation view of the planocentric means for the sensor unit;

FIG. 5 is a central sectional view of the indicator unit adapted for mounting on the dashboard of an automobile;

FIGS. 6 and 7 are sectional views respectively taken substantially along lines 66 and 7-7 of FIG. 5;

FIG. 8 is an elevational view of an electrical contact element forming part of the assembly of FIG. 6;

FIG. 9 is a central sectional elevational view of a remote odometer sensor unit; and

FIGS. 10 and 11 are sectional views taken substantially along respective lines l0l0 and llll of FIG.

DETAILED DESCRIPTION The odometer system illustrated in the drawings, and preferably embodying the present invention, broadly comprises a remote sensor unit A and an indicating unit B for reading out the specific mileage incurred by an automobile. Both units are interconnected by a circuit means C employing a dual path therebetween, the circuit controlling the operation of a motor 10 forming part of the indicating unit. The sensor unit A picks up rotary motion thru a member 15 connected to a component such as a gear within the transmission of the vehicle which turns proportionally to vehicle movement; the sensor unit actuates a switch 11 through a stepdown reduction means 12 to thereby regulate alternatively the closing of one of the parallel paths l3 and 14 of said circuit.

The indicating unit B is conveniently mounted in the panel of the automobile for read-out and has motor 10 arranged to receive electrical energization as permitted by the control circuit to drive a plurality of odometer rolls 16 through a double set of step-down gear reduction means 17 and 18 and incorporating a switch 19 arranged about an intermediate member of the double gear reduction means. Switch 19 is responsive to a predetermined operation of the motor 10. (equivalent to indexing one numeral or degree corresponding to a fractional mile on the first of said rolls) to de-energize the instantaneous circuit path and put the switch into another condition whereby an alternative parallel path is closed in readiness to receive the next energization cycle of the remote sensor unit.

The object of the use of dual electrical paths in conjunction with doubIe-acting switches, is to obtain alternating energy flow to the motor as the sensor switch alternates between positions corresponding to a predetermined distance experienced by the vehicle, preferably 1/80 of a mile for the embodiment of this invention. This is derived from the fact that for the preferred embodiment the member 15 undergoes I000 revolutions for each mile, the output member of means 12 undergoes a 25/ 1 gear reduction to turn 40 times; finally the switch is actuated twice for each revolution of the output member. Thus the sensor switch is cycled for each I/ of a mile experienced by the vehicle.

Turning now to the indicator unit, as the motor operates in response to flow of energy through one of the electrical paths 13 or 14, the switch 14 will be moved by motor 10 to an alternate position (to the other electrical path) after a predetermined number of revolutions of the motor has been experienced. The latter number of revolutions depends on the size and character of the motor, but must move the first odometer roll an arcuate distance to indicate 1/80 of a mile which is less than one full numeral change. Once this has been accomplished, the motor is de-energized due to the switch connecting with the other path, presumably not closed by the sensor switch 11. When the vehicle experiences another 1/80 of a mile movement, the sensor switch will again change position to close on the path already closed by switch 119. As a consequence, energy will again flow to activate the motor and position the odometer rolls for an additional mileage indication equivalent to 1/80 of a mile.

A prime consideration in the development of this invention was'the achievement of high-ratio reduction of rotary movement within space limitations somewhat equivalent to the thickness of a single flat gear. High efficiency, durability and ability to produce relatively high torque at the output member are additional desirable characteristics sought. To accomplish these ends, and turning firstly to the indicating unit B shown in some particularity in FIGS. 5, 3, 6 and 7, a permanent magnet electric motor 10 is connected to a plurality of odometer rolls 16 of conventional construction, through reduction gearing l7 and 18. The permanent magnet motor 10 and reduction gearing are enclosed in a plastic housing 20 and a metallic housing 21 respectively. The housing 20 includes a generally cup-shaped portion 20a closed by an end wall 20b. The motor may be positioned in spaced relationship to the cup-shaped portion. Metallic housing 21 is formed of split portions 21a and 21b, portion 21b being fitted about an extension 20c of housing 20 and held in place by set screws 22. Portion 21a is fastened at 23 to a suitable plastic housing 24 for the odometer rolls; the fasteners extending through to portion 21b.

Drive between the input member 25 and the outpu member 26 of the transmission comprised of gear reducers 17 and 18, follows substantially the following train of elements: input shaft 25, cam 27, pinion 31, transfer element and, pinion 47, and output member 26. The gear reductions employ a novel wobble-type planocentric arrangement herein defined to mean at least two loosely related concentric gears in a common plane 'such that for each planetary cycle of one gear relative to the other, the one gear will undergo only a highly small arcuate movement about its own axis. The camming element 27 is journalled on the input member or shaft 25 of the motor for rotation therewith; the cam 27 is generally circular having a geometric axis or center 28 offset a distance 29 from the axis 30 of the rotatable input member 26 (see FIG. 5). A pinion 31 is mounted on the camming member having a circular internal opening 32 generally commensurate but slightly larger than the annular camming surface 33 and carrying a plurality of radially outwardly projecting serrations or gear teeth 34, the outer extremeties of the serrations having a maximum diameter 35 and the valleys of the serrations determining a minimum diameter 36. The geometric center 28 of the internal opening for the pinion also constitutes a geometric center for the maximum and minimum diameters 35 and 36. A fixed ring gear 38 is mounted within the internal wall 39 of the housing portion 21b. The ring gear 38 has a plurality of radially inwardly projecting serrations 40 complementary in configuration to the serrations 34 of the pinion 31; the minor diameter 41, but not the maximum diameter 42, of the ring gear serrations is greater than the maximum diameter 35 of the pinion serrations. In addition, the geometric center of pinion serrations is offset from the geometric center of the ring gear so that at least one zone 43 or portion of pinion serrations will be in contact with the serrations of the fixed ring gear at any one time (see FIG. 4).

In order to provide a high-ratio step down, the ring gear serrations are here, one greater in number than the pinion gear serrations, 40 teeth to 39 teeth to provide at least a 40 to 1 gear reduction ratio. All of said elements including the pinion, ring gear and cam are substantially coplaner in the sense that their thickness is relatively small compared to a radial dimension and all are substantially in line in a radial direction.

The second gear reducer 18 shall now be described; the use of tandem planocentric means is preferred to achieve a tailored degree of reduction suited for a particular sized motor. The output from the first gear reduction 17 is provided by way of plurality of pins, or in some integral projections 49 extending to one side and parallel to the axis of rotation, said projections 49 are equally circumferentially arranged, fixed at one end 49a to the pinion and have another end 49b extending into an opening 50 provided in a transfer element 45 adapted to receive drive from the gear reduction 17. A plurality of equi-circumferentially arranged openings 50 are provided each having a diameter sufficient to accommodate movement of the projection therein of at least twice the eccentric dimension 29. As the projections 49 are moved by the pinion, they undergo a toroidal path which requires freedom to move within the openings. However, as shown in H6. 4, at least one projection will maintain contact (as at 51) with the wall of an opening at-all times; the contact 51 shifts progressively from projection to projection during operation. The transfer element 45 has an integral portion offset to one side in a plane adjacent thereto to define cam 46 and carry a camming surface 52 similar to thecamming surface 33 of the first gear reduction. Comparable members such as a pinion 47 with the same number of radially outwardly projecting serrations 53 and dimensioning; and a similar fixed ring gear 54 (press-fitted to the internal wall of housingportion 21a) having serrations 55 disposed about the pinion 47. Projections 56 extend from the pinion, the same in number and mounted the same to function to transmit continuous drive to the final output member 26 in the form of an annular disc press-fitted onto the shaft 57 which also supports and mounts the first odometer roll 58 and is lined with similar shafting (not shown) for the remainder of the odometer rolls 59. The member 26 has equi-circumferentially arranged openings with circular walls to receive progressive contact from the projections as previously described in H6. 4.

Because of the compactness of the tandem gear reduction set, a switching mechanism 19 is employed which is disposed substantially within the plane or commensurate to the thickness of the transfer element 45. Member 50' is formed of conductive material so as function in carrying current and is connected to the motor through a bladed contact 62 connected to motor lead 63. Switch blades or contacts 60, 61 which are in electrical contactrespectively with the legs 13 and 14 of the dual circuit and extend inwardly to make tangential contact with the outer edges of the conductive transfer element 46 except as prevented by nonconductive camming means 64 (in the form of discs having camming edges 65 which will limit the radially inward resilient movement of the conductive blades and 61. Each of the switch blades are bifurcated partially to define portions such as 60a and 60b as shown in FIG. 8. The portions thereof are adapted to overlay opposite side edges of the transfer element and are resiliently biased inwardly to make contact with either the outer periphery of the element or the camming edge. Each of the camming plates have an arcuate portion forming camming edges which extends through and are slightly less than 180 so as to maintain each of the switch blades 60 and 61 out of contact with element 46 during a lesser proportion of each revolution comparable to the operation of switch 11 disposed in the remote sensor unit. Blades 61 are shown in contact in the lower portion of FIG. 5 and close an electrical path through circuit leg 13; blade 60 is out of contact as cammed by edge 65 and holds open or interrupts theelectrical path through circuit leg 14.

Turning now to the sensor unit A, it comprises a housing 70 having a portion 70a enclosing a drive pickup assembly 71 and a portion 70b enclosing substantially the gear reduction 12 and switch 11. Assembly 71 has a bearing 72 centrally journalling a pick-up shaft 73. Portion 70a of the housing is nested within portion 70b and the latter has an open end 70c closed by a member 74 through which extends electrical contact elements to be described.

The shaft 73 has an outwardly extending end 73a having a suitable cross section for driving connection to a rotary member forming part of the transmission of an automotive vehicle. Typically, the housing 70 may be mounted through the opening in the transmission casing and suitably sealed. The other end 7312 of the shaft extends into housing portion 70b for connection to a cam 78 forming part of the gear reduction 12. A midsection of the shaft may mount suitable apparatus 75 for providing speed related signals through the use of a magnet and generator assembly. Electrical cable 76 in connection with a winding 77 provides the output for such auxiliary equipment.

The sensor gear reduction 12 comprises the cam 78 in the form of a disc having a circular annular camming surface 79 functioning as such due to an eccentric offset 80 of rotary shaft 73 relative to the geometric center 81 of surface. The camming means 78 is nestably received within a central opening 82 of a pinion 83 carrying a serrated or toothed outer periphery 84. The pinion 83 is eccentrically mounted with respect to the axis 85 of rotation of camming means 78 by defining the opening 82 within the pinion as a circle thereby controlled by the offset surface 79. Disposed about the serrated or toothed periphery 84 of the pinion is a rigidly fixed ring gear 86 having radially inward serrations 87. For purposes of defining a step-down high-ratio conversion, the fixed ring gear contains, here preferably 25 teeth and the pinion has 24. The object is to obtain a single revolution of the pinion 83 for each 25 revolutions of the cam 78. To accomplish this, the maximum diameter 90 of the serrations of the pinion is dimensioned to be less than the maximum diameter 88 of the serrations of the ring gear, but at the same time greater than the minimum diameter 89 of the ring gear serrations. Accordingly, as the camming means undergoes a single rotation, the pinion will shift the zone 91 of engaged or meshed teeth gradually about the ring gear to obtain a relative advancement of the pinion to the ring gear equal to one tooth. Due to the difference in number of teeth between the ring gear and pinion, the pinion gear will advance or make up one tooth position for such revolution; to advance 25 teeth or one complete revolution, the zone 91 will have to undergo 25 revolutions. During such progressive shifting of the engaged teeth, the axis of the pinion undergoes a path travel which is noncircular and can be characterized as a wobble. Due to such wobble movement, a direct positive connection to the output 92 in form of a disc is not desirable. Accordingly, at least one pin integral projection 93 (and here preferably six circumferentially spaced thereabout) are attached to the pinion and extend through a plurality of respective equi-circumferentially spaced openings 94 in the disc 92, the openings having a diameter 95 greater than the diameter of each pin 96. Thus as the pinion undergoes itsnon-circular wobble movement, at least one projection will maintain contact with the wall of one of the openings 94 and such contact will shift progressively from projection to projection as each undergoes a toroidal movement.

To obtain compactness in keeping with the ultracompactness of gear reduction 12, double-acting switch 11 comprises a conductive plate 97 defined in the shape of a sector of a circle (see FIG. 2) and is attached to side 92a of output member 92. The apex 98 of the plate sector is connected to ground via stamped circular conductive contact 99 having a finger 100 resiliently biased to engage the apex at all times. Resiliently biased conductive fingers 101 and 102 each have contact buttons 103 and 104, respectively, and are arranged to engage diametrically opposite locations on output member 92, the sector of plate 97 must be less than 180 so that only electrical path can ever be closed at any one time. For example, as output member 92 turns, sector plate 97 will sweep switch 12 so that contact button 104 is engaged with plate 97; this completes an electrical path through leg 13 of the dual circuit (connected via conductive bracket 105 to electrical wiring) allowing energy to flow to motor 10 if switch 19 is properly conditioned. After an additional /a revolution of output member 92, contact button 104 will engage only the non-conductive disc 92 and not the plate sector 97. However, contact button 103 now can engage plate 97 completing a path through leg 14 (connected via bracket 106 to electrical wiring). Thus, the rotary position of member 92 is translated into an electrical communication relay whereby a motor may be sequentially energized to operate odometer rolls.

I claim as my invention: I

1. In a vehicular odometer system having an electrical circuit for energizing said system and a remote sensor unit to affect said circuit in conformity with vehicle movement, a panel-mounted indicating unit comprismg:

a. an electrical motor,

b. a plurality of odometer rolls adapted to be rotatably driven by said motor, and

c. planocentric means drivingly connecting said motor with said rolls and effective to provide a high ratio step-down in rotary movement therebetween not less than 25 to l.

2. In a vehicular odometer system having an indicating unit with motor driven odometer rolls, an electrical circuit for energizing said motor driven rolls, a remote sensor unit affecting said circuit in conformity with vehicle movement, the combination comprising:

a. parallel arranged electrical paths interposed in said circuit and extending between said units,

b. means providing electrical switches at each of said units, one of said switches being effective to alternate contact between said paths in accordance with a predetermined actuation of the sensor unit, and the other switch being effective to alternate contact with each of said paths in accordance with a predetermined rotation of said motor driven rolls,

and

planocentric means in said indicating unit serving as the sole driving connection between said rolls and motor, and providing a high ratio step-down in rotary movement therebetween with a ratio no less than 25 to 1.

3. The combination as in claim 2, in which said planocentric means comprises:

a. means drivingly connected to said motor and providing at least one annular camming surface,

b. a pinion eccentrically mounted in the plane of said camming surface for rotary movement as urged by camming surface, said pinion having annularly arranged serrations and having means drivingly connecting to said odometer rolls, and

c. a fixed ring in the plane of said camming surface having annularly arranged serrations for engagement at any one time with only a portion of the serrations on said pinion in a zone, said serrations of said ring being greater in number than the serrations of said pinion whereby predetermined multiples of rotation of said camming means will result in one rotation of said zone of engagement between said pinion ring thereby imparting one revolution to said pinion.

4. The combination as in claim 3, in which said planocentric means comprises a pair of assemblies in series, each assembly having anannular camming surface, and fixed ring whereby the step-down reduction is substantially increased.

5. The combination as in claim 3, in which said second switch comprises an assembly lying substantially in the plane of said planocentric means, the switch having a pair of nonconductive camming plates carried on opposite sides of a member of said means, each camming plate having an edge extending radially beyond the outer periphery of said member an arcuate extent equal to an are less than said switch further comprising a pair of resilient contact fingers, each in electrical communication with one of said paths, each finger being mounted for resilient contact with the outer periphery of said member or-cam plate, said member being conductive. 

1. In a vehicular odometer system having an electrical circuit for energizing said system and a remote sensor unit to affect said circuit in conformity with vehicle movement, a panel-mounted indicating unit comprising: a. an electrical motor, b. a plurality of odometer rolls adapted to be rotatably driven by said motor, and c. planocentric means drivingly connecting said motor with said rolls and effective to provide a high ratio step-down in rotary movement therebetween not less than 25 to
 1. 2. In a vehicular odometer system having an indicating unit with motor driven odometer rolls, an electrical circuit for energizing said motor driven rolls, a remote sensor unit affecting said circuit in conformity with vehicle movement, the combination comprising: a. parallel arranged electrical paths interposed in said circuit and extending between said units, b. means providing electrical switches at each of said units, one of said switches being effective to alternate contact between said paths in accordance with a predetermined actuation of the sensor unit, and the other switch being effective to alternate contact with each of said paths in accordance with a predetermined rotation of said motor driven rolls, and c. planocentric means in said indicating unit serving as the sole driving connection between said rolls and motor, and providing a high ratio step-down in rotary movement therebetween with a ratio no less than 25 to
 1. 3. The combination as in claim 2, in which said planocentric means comprises: a. means drivingly connected to said motor and providing at least one annular camming surface, b. a pinion eccentrically mounted in the plane of said camming surface for rotary movement as urged by camming surface, said pinion having annularly arranged serrations and having means drivingly connecting to said odometer rolls, and c. a fixed ring in the plane of said camming surface having annularly arranged serrations for engagement at any one time with only a portion of the serrations on said pinion in a zone, said serrations of said ring being greater in number than the serrations of said pinion whereby predetermined multiples of rotation of said camming means will result in one rotation of said zone of engagement between said pinion ring thereby imparting one revolution to said pinion.
 4. The combination as in claim 3, in which said planocentric means comprises a pair of assemblies in series, each assembly having an annular camming surface, and fixed ring whereby the step-down reduction is substantially increased.
 5. The combination as in claim 3, in which said second switch comprises an assembly lying substantially in the plane of said planocentric means, the switch having a pair of nonconductive camming plates carried on opposite sides of a member of said means, each camming plate having an edge extending radially beyond the outer periphery of said member an arcuate extent equal to an arc less than 180*, said switch further comprising a pair of resilient contact fingers, each in electrical communication with one of said paths, each finger being mounted for resilient contact with the outer periphery of said member or cam plate, said member being conductive. 